This invention relates to the field of optoelectronic devices, and more particularly, to optical transceivers and remote optical sensors.
In many applications, electrical wires are used to deliver electrical power to, and retrieve signals from, a remote device such as a sensor. For example, in aircraft applications, electrical wires are commonly used to deliver electrical power to, and retrieve signals from, remotely located sensors, such as flap position sensors, temperature sensors, pressure sensors, etc. In industrial applications, electrical wires are commonly used to deliver electrical power to, and retrieval signals from, a wide variety of remotely located sensors, such as position, pressure, temperature and other sensors. In medical applications, electrical wires have been used to deliver electrical power to and retrieve signals from sensors and/or other devices. In some cases, sensors or other electrical devices have even been placed in catheters, which are inserted into the body.
In each of these applications and other applications, the use of electrical wires can present difficulties. For example, in some applications, lighting strikes may make long wire runs hazardous or at least less reliable. Other environmental electrical noise can also disrupt or reduce the reliability of such systems. In addition, long electrical wire runs can present significant capacitance, inductance, and resistance, which in some applications, can distort the sensor signals and/or reduce the speed at which the sensor signals can be retrieved. For some medical applications, such as catheter applications, it is often undesirable to string electrical wires through a catheter that is inserted into the body, and in particular, when the catheter is inserted near the heart or brain of a patient. The current passing through the electrical wires can, in some cases, pose a threat to the patient. In addition, and during certain medical procedures, the electrical wires can be subject to intense electromagnetic fields or other harsh environmental conditions, which may make the use of electrical wires hazardous or at least less reliable.
One approach for reducing some of these difficulties is to use a remotely located battery to power the remote sensor. However, the use of batteries has a number of disadvantages. For example, batteries are often expensive and only last a limited time. Even when a battery is appropriate, the sensor output signals must still be retrieved from the sensor, which in many cases, may require the use of electrical wires.
Another approach for reducing some of the above-mentioned difficulties presented by electrical wires is to use optical fibers to deliver power to, and/or retrieve signals from, a remote sensor or other device. A first fiber may be used to deliver optical power to a remote sensor. The optical power may be converted to electrical power by a remotely located photo diode or the like. The electrical power may then be used to power a laser or light-emitting diode or the like, which provides an optical signal that represents the sensor output signal back through a second optical fiber. This approach has some advantages, including increased electromagnetic interference immunity. However, in many cases, two separate optical fibers must be used—one for providing power to the remote sensor and one for retrieving the sensor output signals from the remote sensor. A single fiber may be used in some cases, but because the light-emitting diode used for receiving the optical power signal and the laser or light-emitting diode used to provide the sensor output signals are often laterally offset from one another (i.e. not along a common optical axis), a complex optical splitter/combiner must also be used. Such an optical splitter/combiner can be expensive, bulky and in many cases difficult to maintain in a proper optical alignment position.